Sheet handlers are well known and, generally, such sheet handlers have a defined path through which sheet material is transported to and from one or more process stations. In image input devices, electrophotographic devices, ink jet printing devices and other such devices, sheet handling devices are employed to sequentially transport sheet material (i.e., sheets of paper and paper-like substrates, such as mylar, vellum, and the like and hereinafter collectively referred to as sheets) to and from image processing stations, such as scanning devices, imaging devices, fusing stations, imprinting stations, and the like.
Sheet handlers of the type to which this invention relates include both sheet handlers which are known as document handlers for sequentially feeding individual documents from a document input station to a document image processing station and then to a document output station, as well as sheet handlers of the type for sequentially feeding individual copy sheets from a copy sheet input station, to a copy sheet imprinting, and to a copy output station. In general, in devices having a flat surface or a relatively flat surface upon which an image processing operation occurs a sheet handler is employed to transport the sheets across the surface. For example, in document handling devices having a imaging platen, in general, a roller, friction belt, or vacuum belt transport is employed to move a document across the surface.
These devices are functional, and they produce reasonably satisfactory results. However, they also tend to be somewhat expensive, not entirely simple, and not always entirely effective. Furthermore, with some or all of these devices, actuated registration means such as scuffer wheels, cross rollers and the like must be employed either concurrently with the drive mechanism or at an upstream portion of the path so that the transported sheets are registered at a processing station. Thus, there exists a need for a relatively simple, low cost apparatus for transporting documents and sheets in general across a flat surface to a process station in a registered manner.
The following disclosures may be relevant to various aspects of the present invention.